Titles Won (2): Rome, Cincinnati (2-2 in finals)
Best Grand Slam Result: R-Up (1): Wimbledon
Win/Loss Record: 43-12
Record Against Top 10: 5-5 (4-4 excluding retirements)
SEC History: Fifth appearance; Champion 2004, R-Up 2007
It's hard to believe Sharapova, still only 24, is making her fifth appearance at the WTA Championships but first since 2007. On that occasion she was runner-up to Justine Henin in a marathon final. But three years earlier - the year she won Wimbledon - she defeated Serena Williams at the season finale in Los Angeles. Both years in between Sharapova reached the semifinals, and the way she's played this year, another strong showing seems likely.
It is now exactly three years since the Russian superstar underwent shoulder surgery, and 29 months since her return to the WTA at Warsaw in May 2009. For the first 18 months or so she showed flashes of the brilliance that took her to No.1 as a teenager, while also posting erratic results. However, in 2011 she has re-established herself as one of the most reliable performers on the circuit, reflected in her rise back up to No.2 on the rankings.
Her season hasn't been perfect - she lost to Andrea Petkovic in the fourth round at the Australian Open, and to Flavia Pennetta in the third round at Flushing Meadows. And she was surprised by Greta Arn at Auckland and Galina Voskoboeva at Toronto. But the highlights have been many.
In August, Sharapova won her 24th career title at Cincinnati, recovering from a 64 20 deficit against Jelena Jankovic in the final to emphasize her status as the queen of the three-setters: heading into Istanbul she is 10-1 on that count, the sole blemish being that loss to Pennetta. (She is also an impressive 8-1 in tie-breaks, so watch out if things get close.) But the real breakthrough came at Rome in May, where she swept past Victoria Azarenka, Caroline Wozniacki and Samantha Stosur to claim her first title on red clay.
This was followed by a semifinal run at Roland Garros - her first major semi since her triumph at the Australian Open in 2008 - and then, back on her beloved grass, her second Wimbledon final, where Petra Kvitova had her day. Sharapova also delivered strong results at Indian Wells, where she fell to Wozniacki in the semis, and Miami, where Azarenka prevailed.
Sharapova is arguably playing better than ever and, what's more, she exudes a new air of contentment. Although forced to retire in the quarters at Tokyo with a left ankle injury that kept her out of the China Open, she arrived in Istanbul early to prepare. The competitive spirit is as strong as ever, it seems.